Impact of myeloperoxidase-derived oxidants on the product profile of human 5-lipoxygenase |
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| Institution: | 1. Institute for Medical Physics and Biophysics, Medical Faculty, Leipzig University, Leipzig, Germany;2. Translational Center for Regenerative Medicine Leipzig, Leipzig University, Leipzig, Germany;3. Institute of Laboratory Medicine, Clinical Chemistry, and Molecular Diagnostics, University Hospital Leipzig, Leipzig, Germany;4. LIFE–Leipzig Research Center for Civilization Diseases, Universität Leipzig, Leipzig, Germany;3. Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Korea;4. Department of Microbiology, University of Illinois, Urbana, Illinois 61801;1. Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China;2. Department of Comparative Biosciences and the Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, WI 53706, United States;1. Department of Adult Psychiatry, Medical University of Lodz, Lodz, Poland;2. Department of Medical Biochemistry, Medical University of Lodz, Lodz, Poland;1. Nephropath, Little Rock, Arkansas;2. DNASTAR, Madison, Wisconsin;1. Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea;2. Fish Vaccine Development Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea;3. Biotechnology Research Division, National Fisheries Research and Development Institute, 408-1 Sirang-ri, Gijang-up, Gijang-gun, Busan 619-705, Republic of Korea;4. Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea |
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| Abstract: | Human 5-lipoxygenase (5-LOX) oxidizes arachidonic acid to 5S-hydroperoxy-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-HpETE) and leukotriene (LT) A4. In neutrophils, LTA4 is further converted to the potent chemoattractant LTB4. These cells also contain the heme enzyme myeloperoxidase (MPO), which produces several potent oxidants such as hypochlorous acid (HOCl), which are involved in pathogen defense and immune regulation. Here, we addressed the question whether MPO-derived oxidants are able to affect the activity of 5-LOX and the product profile of this enzyme. Human 5-LOX was incubated with increasing amounts of HOCl or HOBr. Afterward, arachidonic acid metabolites of 5-LOX were analyzed by reverse-phase high-performance liquid chromatography as well as by liquid chromatography–electrospray ionization–tandem mass spectrometry. The incubation of 5-LOX with the MPO-derived oxidants significantly changed the product profile of 5-LOX. Thereby, HOCl and HOBr increased the ratio of 5-H(p)ETE to 6-trans-LTB4 in a concentration-dependent manner. At low oxidant concentrations, there was a strong decrease in the yield of 6-trans-LTB4, whereas 5-HpETE did not change or increased. Additionally, the formation of 8-HpETE and 12-HpETE by 5-LOX rose slightly with increasing HOCl and HOBr. Comparable results were obtained with the MPO–H2O2–Cl− system when glucose oxidase and glucose were applied as a source of H2O2. This was necessary because of a strong impairment of 5-LOX activity by H2O2. In summary, MPO-derived oxidants showed a considerable impact on 5-LOX, impairing the epoxidation of 5-HpETE, whereas the hydroperoxidation of arachidonic acid was unaffected. Apparently, this was caused by an oxidative modification of critical amino acid residues of 5-LOX. Further work is necessary to assess the specific type and position of oxidation in the substrate-binding cavity of 5-LOX and to specify whether this interaction between 5-LOX and MPO-derived oxidants also takes place in stimulated neutrophils. |
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| Keywords: | Eicosanoids Arachidonic acid HOCl HOBr Neutrophils Free radicals |
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